Attention should be paid to summer and winter temperatures. We must remember that plants when placed in bonsai pots live with “reduced resources” therefore it is our job to pay due caution.
If in nature the roots of trees are protected by a thick layer of earth that keeps them at a more or less constant temperature in all seasons (10-15 degrees), this is not the case when they are placed in a bonsai pot. Particularly in summer the temperatures of the pot and of the roots can rise a lot (up to 60 degrees!), while in winter they drop down to room temperature.
What can be the remedies then?
In summer it is good to lift the bonsai from the floor and place them in the shelter of a shading tent in the hottest months (July-August) and, if necessary, place under pots with expanded clay and water (but from which the plants cannot absorb water directly).
In winter, however, it is always advisable to keep the pots in a position raised from the floor, mulch with leaves (you can also use a larger external pot containing plasters), use polystyrene containers around the pots or even bury the clod in full earth (especially in areas in which winters are more severe).